Researchers have uncovered the fossil of an extinct bird with a mouthful of tooth-like spikes and wings just smaller than a World War I fighter plane's. At 20 to 24 feet from wingtip to wingtip, the new species had the biggest wingspan of any known bird, outstripping the next-biggest feathered flyer by 15% or more.

The bird "is more like a dragon out of the Game of Thrones show than anything alive today. It's so spectacularly weird," says paleontologist Daniel Ksepka of the Bruce Museum in Greenwich, Conn., author of a new study describing the bird.

"If you could imagine the shadow this thing would've cast back in the day, 'awe-inspiring' and 'terror-inspiring' would be appropriate phrases," says bird paleontologist Julia Clarke of the University of Texas, Austin, who was not connected to the new study.

The giant bird, which lived roughly 25 million years ago, might have scooped its prey from the ocean's surface, clamping onto any wriggling seafood with its "teeth," which were actually pointy knobs of bone. Or perhaps it led a life of crime, robbing other birds of their catch.

"When a 24-foot-wingspan bird says, 'Give me your lunch,' you probably better do what it says," says Ksepka, to explain how a bird with low maneuverability could be a successful thief.

Perhaps fittingly, the fossil was discovered at an airport in Charleston, S.C., in 1983, as workers prepared to build a new terminal. The first part of its scientific name, Pelagornis sandersi, means "marine bird." The second part honors paleontologist Albert Sanders, who excavated the specimen.

By some calculations, this monster was literally too big to fly, because as a bird gets super-large, the power it needs to stay aloft outstrips the power it can generate from its muscles. But the bony-toothed bird's delicate bones and "dinky" legs show it was definitely a flyer, Ksepka says.

An analysis of its shape and size suggests the bird could travel for long distances while expending little energy, Ksepka reports in this week's Proceedings of the National Academy of Sciences. And it could probably sustain speeds of 10 meters per second, matching Usain Bolt's speed in the 100-meter dash, Ksepka says.

Paleontologist Michael Habib of the University of Southern California generally agrees with Ksepka's assessment of the bird's size and flying abilities. Unlike other researchers, he didn't rule out such an enormous flying bird, but he still calls the find "very exciting … It refutes some of the prior estimates of maximum size in seabirds." These birds were not, however, bigger than the biggest pterosaurs, flying reptiles that died out before the new bird species took wing.

But Katsufumi Sato of the University of Tokyo says via e-mail that he has doubts about the new bird's wingspan. Estimating feather length, as this study does to estimate wing length, is difficult, he says.

Ksepka responds that he used multiple methods of estimating feather length; all point to a wingspan of at least 20 feet. The true mystery, Ksepka says, is why this big bird and its kin, which were also large, vanished after ruling the skies around the globe from just after the time of the dinosaurs until just before modern humans evolved.

"They lasted more than 50 million years. That's phenomenally successful," Ksepka says. "And then they died out before we got to see them."